The Desert Sunreports the U.S. Supreme Court announced on November 27, 2017, it will not hear an appeal by California water agencies in the Agua Caliente Band of Cahuilla Indians’ landmark lawsuit asserting rights to groundwater beneath the tribe’s reservation.

The Desert Water Agency and the Coachella Valley Water District had appealed to challenge a decision by the Ninth Circuit Court of Appeals, which ruled the tribe has a right to groundwater dating back to the federal government’s creation of the reservation in the 1870s.

The Supreme Court’s denial of the agencies’ petition means the tribe has prevailed in winning legal backing for its claim to groundwater rights—a victory expected to change how decisions are made about management of the desert aquifer in Palm Springs and surrounding communities.

The case will likely have far-reaching effects for Indian water rights throughout the West and across the country, according to The Desert Sun, giving tribes more of a say and redrawing the lines in disputes over water. By establishing that the Agua Caliente tribe holds special federally reserved rights to groundwater, the court decisions so far in the case are expected to strengthen other tribes’ positions in negotiations and court battles.

The two water districts said in a statement they now expect a “lengthy and expensive legal process.”

Tribes and water suppliers across the West are closely monitoring the case.

According to The Desert Sun, a list of 35 tribes and five tribal organizations filed a brief in support of the Agua Caliente tribe last year. They included the Spokane Tribe of Indians in Washington and the Pyramid Lake Paiute Tribe in Nevada, as well as other tribes in California.

If the Supreme Court had agreed to hear the case, it would have had a unique opportunity to rule on the question of whether tribes hold special federal “reserved rights” to groundwater as well as surface water, and to define more clearly the boundaries between state-administered water rights and federal water rights.

Now that the Supreme Court has let the lower court’s ruling stand, it will be up to lower courts to clarify lingering ambiguities in the established law.